This invention relates to the art of pumps and, more particularly, to manually operated pumps for testing fluid lines under pressure for leaks.
It is of course well known to test lines in a fluid system such as a hydraulic or water supply system for leaks following installation of the system or the repair of lines therein. The use of manually operated lever type fluid pumps for such testing is likewise well known. Such pumps generally include a container for fluid to be pumped into the system to be tested, and a hand lever actuated piston and cylinder type pump having suction and discharge strokes in response to displacement of the operating lever in opposite directions about a lever axis. The inlet side of the pump is in flow communication with fluid in the container, and the discharge side of the pump is provided with a hose or the like which is adapted to be coupled with the system for delivering fluid thereto from the pump. The system to be tested is initially filled with fluid, and the lever is then displaced in opposite directions about its pivot axis to pump additional fluid into the system until the desired test pressure is attained which may, for example, be 50 bar or 725 psi. Generally, the pump includes a pressure gauge for indicating the system pressure and for determining the presence or absence of leaks in that the system pressure should not fall during the test period if there are no leaks.
In pressure testing pumps of the foregoing character heretofore available the hand lever is pivotally mounted on the container at one end thereof and extends to the opposite end of the container, the pump cylinder is fixed relative to the container, and the piston rod of the pump piston is pivotally attached to the hand lever at a location spaced from the pivot axis for the lever. Pulling up on the hand lever displaces the piston in the cylinder to provide the suction stroke, and pushing down on the hand lever displaces the piston to provide the discharge stroke. The location of the pivot axis for the piston rod relative to the pivot axis for the lever, the size of the piston and the length of the hand lever are variables which cooperatively determine the per stroke volume displacement capability for the pump and the leverage available for displacing the piston during the discharge stroke. High volume flow is desired to minimize the number of strokes and thus the work required by the operator in using the test pump, and good leverage is desired during the discharge stroke, and especially as the test pressure is approached, to enable attaining a high test pressure and to minimize the physical force required to be applied to the lever by the operator as the system pressure increases.
For a given size piston in the pumps heretofore available, initial pumping of additional fluid into the system can be achieved with a full stroke displacement of the hand lever which may, for example, be an angular displacement of about 80.degree. to 90.degree. or more about the lever axis. As the test pressure is approached, however, it is necessary because of the location of the pivot axis for the piston rod relative to the lever axis to limit the stroke of the hand lever to less than about 30.degree. in order for the operator to physically displace the hand lever to displace the piston and thus fluid into the system at or near the test pressure. At lever angle greater than about 30.degree., it is either impossible for the average operator to apply sufficient force to displace the piston, or it is impossible to move the piston because of the side thrust imposed thereon by the lever-piston rod relationship. Even with a short stroke of 30.degree. or less, the test pumps heretofore available require a force on the hand lever of from about 100 pounds to 140 pounds to achieve piston displacement at a test pressure of 50 bar or 725 psi. Thus, operation of the pump as the test pressure is approached is both difficult and requires undesirably high physical exertion by the operator If the piston rod connection is moved closer to the lever axis and/or the diameter of the piston is reduced, either or both of which will increase the available leverage, the volume displacement capability is reduced, whereby more strokes are required to attain the test pressure and, thus, more time is required to test a system with very little if any reduction in the overall physical exertion required of the operator. In order to optimize the available leverage, the operating end of the hand lever extends beyond the corresponding end of the container for the liquid. While this increase the leverage, such a lever extension is potentially hazardous. In this respect, as the system pressure increases and a greater force application to the end of the lever is required to discharge fluid from the pump, the downward force applied to the end of the lever at a point beyond the end of the container can cause the container to tilt about the latter end thereof. Such instability can cause liquid to spill from the container, subjects the operator to potential injury, and subjects the component parts of the pump to potential damage.